Electrosurgical instruments have been used for many years in high-frequency surgery, in order to coagulate and/or cut biological tissue. In this process a high-frequency current is conducted through the tissue to be treated, so that the latter becomes altered owing to protein coagulation and dehydration. The tissue thus contracts in such a way that the vessels are closed and bleeding is stanched. A subsequent increase in current density causes an explosion-like evaporation of the tissue fluid and tearing apart of the cell membranes, so that the tissue is completely transected. Procedures of this kind present the advantage, as opposed to a purely mechanical cutting process, that hemostasis is produced at the cut edges.
The employment of bipolar instruments is becoming increasingly significant, because the current intensities are less than in the case of monopolar instruments. It is especially advantageous that the current route between the electrode parts of bipolar instruments can be calculated and does not pass for large distances through the patient's body.
Bipolar instruments comprise substantially two clamp parts having an articulated connection to one another, with gripping devices provided at their proximal ends for manipulation of the clamp parts. At distal ends of the clamp parts there are electrode parts for grasping tissue and for conducting a coagulation current through the tissue. The HF current generated by a HF generator is conducted to the electrode parts of the bipolar instrument by way of current-supply devices.
When the bipolar instruments described above are being used, after a coagulation procedure cutting instruments must be employed for the final transection of the coagulated tissue. The cut is carried out with either a surgical scissors or a HF cutting instrument. However, this use of different instruments requires interruption of the surgical operation, which is thus unnecessarily prolonged.
To counteract this disadvantage, multifunctional instruments have meanwhile come into use, designed at least for both coagulation and cutting. Such an instrument is known, for example, from the document DE 199 15 060 A1, with which diverse working devices such as forceps, hooks or even ultrasonic devices and electrodes for cutting or coagulation can be put into operation by actuators. A control unit enables the planned working steps to be carried out consecutively.
The embodiment of a multifunctional instrument described there, however, has the disadvantage that coagulating and cutting are still two different treatments, to be performed successively in time, even though the steps can be carried out by single instrument. A first procedure must therefore be intentionally ended, after which a second procedure is, again intentionally, begun. Between these procedures at least one manipulation must be done, namely to activate the multifunctional instrument for the next task. This, too, unnecessarily delays the course of the operation. In addition, during the activation of a procedure errors can occur regarding the setting of appropriate operating parameters, such as a suitable HF current.
Known multifunctional instruments of the kind described above furthermore comprise poles that are electrically insulated from one another, being provided for coagulation and for cutting respectively, so that the instrument must have relatively large dimensions. This distinctly limits the surgeon's freedom of movement in the operation region and hence limits the range of functions for which the known instruments can be used.